Release device for electrical switches

ABSTRACT

A device for initiating release of the contacts of an electrical switch includes an actuating rod which is tensioned in the upward, release direction, but which is retained in a downward position, until released, by means of a cylindric roll operating in an angular slot and which is maintained in a state of unstable equilibrium by the magnetic attractive force of a hold-release magnet. The angular slot and cylindric roll mechanism is so designed that when the release device is in its &#39;&#39;&#39;&#39;hold&#39;&#39;&#39;&#39; position, a releatively high tensional force exerted on the actuating rod tending to pull it upward is counter-balanced by a much smaller magnetic force.

United States Patent [1 91 Biihler et a1.

RELEASE DEVICE FOR ELECTRICAL SWITCHES Inventors: Karl Biihler,Nussbaumen; Dieter Floessel, Fislisbach, both of SwitzerlandAktiengesellschatt Brown, Boveri & Cie, Baden, Switzerland Filed: Apr.4, 1972 Appl. No.: 240,950

Assignee:

Foreign Application Priority Data Apr. 26, 1971 Switzerland 6060/71 US.Cl. 335/190, 200/153 Int Cl. l-l0lh 3/42 Field of Search 335/190, 26'

References Cited UNITED STATES PATENTS 4/1966 Lindsay 335/190 1 Oct. 23,1973 2,994,753 8/1961 Astleford, Jr. et a1 335/26 3,209,101 9/1965 Peeket a1. 335/190 3,602,676 8/1971 Mrenna et a1. 200/153 G PrimaryExaminer-Harold Broome Attorney-Ralph E. Parker et a1.

[57] ABSTRACT A device for initiating release of the contacts of anelectrical switch includes an actuating rod which is tensioned in theupward, release direction, but which is retained in a downward position,until released, by I means of a cylindric roll operating in an angularslot and which is maintained in a state of unstable equilibrium by themagnetic attractive force of a hold-release magnet. The angular slot andcylindric roll mechanism is so designed that when the release device isin its hold position, a releatively high tensional force exerted on theactuating rod tending to pull it upward is counter-balanced by a muchsmaller magnetic force.

4 Claims, 4 Drawing Figures 1 RELEASE DEVICE FOR ELECTRICAL SWITCHES Thepresent invention relates to an improved release device for initiatingoperation of the mechanism of an electric switch by means of which thecontacts are actuated from a closed to an open position, or vice-versa.

In general, the release device includes a cylindric roll which performsablocking function preventing actuation of the switch contacts untilreleased, the roll being connected to a contact actuating component ofthe switch mechanism which is subjected to a tensional force, and beingretained in an unstable state of rest by the attractive force of amagnet until released by a reduction in the magnetic holding force.

It is known from the prior art, e.g., Swiss patent No.

315,719, that periodically movable contact devices can be protectedagainst interference from fault currents by means including a componentsubjected to the action of a spring which is supported with theassistance of a roll body and a thrust bearing. The roll body isretained in its blocked position by the armature of a magnet. Thearmature to be actuated is relative large and for this reason therelease operation takes place with a considerable degree of inertia.Moreover, in this case, suspension of the tensioned component at theroll by means of an edge and cross beam arrangement is relativelycomplicated.

German patent application No. 1,119,982, now laid open for publicinspection, discloses a release device for electrical, fast-actionswitches which includes a cylindric blocking roll retained in a labile,i.e., unstable position of rest by magnetic force when the switch is inits blocked position. In that application, the roll cylinder utilized inthe blocking mechanism also functions as the armature of the holdingmagnet. This specific arrangement restricts selection of the materialfor the roll cylinder for two reasons, one being the necessity forkeeping wear abrasion to a minimum and the other being the importance ofits magnetic properties.

The object of the present invention is to provide an improvedconstruction for a switch contact release device of the type generallydescribed which is not only relatively simple and inexpensive tomanufacture but which is fast-acting and wear-resistant.

In general the improved release device, includes a cylindric roll bodyconnected to a contact actuating com ponent of the switch such as avertically extending rod which is subjected to a tensional stress whenthe switch contacts are in a rest position, either closed or open, therollbody operating within an angular slot and being maintained in astate of unstable equilibrium by the magnetic attractive force of ahold-release magnet. The angular slot and cylindric roll mechanism is sodesigned that when the release device is in its hold position, arelatively high tensional force exerted on the actuating rod tending tomove it upward is counterbalanced by a relatively much smaller magneticforce. This is accomplished by a unique mechanical advantage achieved inthe force train and particularly at the slot and cylindric rollcomponents whereby the tensional force drawing upwardly on the actuatingrod exerts only a relatively small horizontal break-a-way component atthe armature of the hold-release magnet. However, as soon as the releasetakes place, the vertical component of the tensional force drawing theactuating rod upward increases rapidly with the result that the contactsof the switch are quickly actuated.

The foregoing as well as other objects and advantages inherent in theinventive concept will become more apparent from the followingdescription of three different embodiments thereof and from theaccompanying drawings wherein:

FIG. 1 is a vertical central sectional view of one embodiment of therelease device with certain components shown in elevation;

FIG. 2 is a horizontal section taken on line A A of FIG. 1;

FIG. 3 is a vertical view showing a modified construction for theangular slot and cylindric roll components of the mechanism by which thedesired initial mechanical advantage at the hold-release magnet isachieved; and

FIG. 4 is a view similar to FIG. 3 and illustrating another modifiedconstruction for the angular slot and cylindric roll components of themechanism by which the desired result is achieved.

With reference now to the drawings and to FIGS. 1 and 2 in particular,the improved release device for initiating actuation of the contacts ofan electrical switch in one direction or the other, to effect closure oropening of the contacts, includes a two-part housing" 1 bolted togetherand in which is mounted a hold-release magnet 2. Magnet 2 includes apair of pole shoes 2a between which is seated an armature 3. The latteris normally retained in place against the pole shoes by the magneticflux produced by the magnet. Accordingly, the magnet 2 can be of theelecrical type wherein a coil is provided to produce the magnetic fluxwhich holds the armature in place, or preferably the magnet can be ofthe permanent type which produces its own magnetic flux, and a releasecoil can be wound onto the magnet structure which when energized willproduce a demagnetizing magnetic flux that has a diretion opposite tothat produced by the magnet, thus resulting in an overall weakening ofthe total magnetic flux acting to hold the armature in place against thepole shoes with the result that the armature is released when pulled inthe break-a-way direction.

Armature 3 is displaceable parallel to itself in a horizontal directionwithin the housing 1 towards and away from the magnet pole shoes 2a byguideways la which receive opposite end portions of the armature, and apair of rigid draw straps 4 are pivotally connected respectively at oneend to opposite end portions of armature 3. The opposite ends of straps4 are pivotally connected to and support for rotation stub shafts at theopposite ends of a cylindrical roll 5 which operates within asubstantially L-shaped slot 9 provided in a guide plate 10 which issecured within housing 1 by means of bolts 11. As is seen in FIG. 1, theslotted plate 10 extends vertically and the lower part 9a of the guideslot 9 for roll 5 slopes slightly downward from the horizontal. Theupper part 9b of the slot 9 extends vertically upward.

Pivotally connected to each end portion of roll 5 are the ends of asecond pair of rigid draw straps 6, the opposite ends of these strapsbeing articulated to the lower end 7a of an actuating rod 7 whichextends in a vertically upward direction, the rod also being providedwith a cylindric guide plate 71) slidable within an upwardly extendingguide tube 8 having the lower end thereof secured to an upwardlyextending tubular outlet lb of housing 1. As is evident from FIG. 1, themechanism thus described operates between one limit position shown insolid lines, i.e., a hole position, wherein roll is located in the lowerpart 9a of slot 9 near the bend in the slot and armature 3 is engagedwith the pole shoes 2a, to its other limit position depicted in dash-dotlines i.e., a release position wherein roll 5 has been shifted aroundthe bend into and upward along the vertical part 9b of the slot, andarmature 3 has been shifted to the left and thus disengaged from thepole shoes.

Rod 7 continues upward into other parts of the overall switch structure,not illustrated, and is continuously subjected to a tensional force inthe upward direction when the mechanism is in the hold position. Whenrod 7 is released by release of the magnet armature 3, it movesupwardand functions to effect actuation of the switch contacts from a closedto open position, or vice versa. This is commonly done by using rod 7 tocontrol a blast valve which moves to an open position as soon as rod 7is released, whereupon a pressurized gas is caused to flow to the switchcontact chamber and to actuate a drive mechanism for the contacts, theblast valve being thereafter closed and causing rod 7 to be shifteddownwardly by suitable. mechanism, e.g., a pneumatic piston, to thestarting position whereby armature3 is shifted back into engagement withthe pole shoes 2a, and'rod 7 is thereby held in the unstable downwardposition until it is once again desired to actuate the switch contacts.None of the above-referred to switch structure has been illustratedsince it is well known and does not per se constitute part of theinventive concept.

The present invention resides in the novel interconnections between themagnet armature 3 and release rod 7 whereby a relatively great pulling(upward) force which exists on rod 7 is retained in balance, i.e., in astate of unstable equilibrium by use of a relatively small magneticholding'force. This is due to the fact that roll cylinder 5 ismaintained in the slightly downward sloped portion 9a of the angularslot 9 whereby the force acting in the upward direction on rod 7possesses only a relatively small horizontal break-a-way component atarmature 3. In addition to being able to retain armature 3 in theunstable hold position with a rather small magnetic structure, therelease mechanism is also most efficient, fast acting andwear-resistant.

In the modified embodiment of the invention as illustrated in FIG. 3,the components which correspond in structure and function to those inFIGS. 1 and 2 have been assigned the same reference numerals. Thedifference between this embodiment and the previous one is thatthe lowerend 9a of the angular slot 9 is horizontal and co-axial with theguideways 1a of the housing for the magnet annature 3. The desiredmechanical advantage of requiring a relatively small amount of mag netforce to control a rather large amount of upward force exerted on rod 7is achieved in that when the release mechanism is in the hold positionas depicted in FIG. 3, the draw straps 6 have a slight inclinationrelative to the vertical direction of movement of rod 7. In this manner,only a small horizontal component of force is exerted on'armature 3 inthe break-a-way direction, i.e., to the left.

In the further modified embodiment of the invention as illustrated inFIG. 4, which is somewhat similar to FIG. 3, the lower part 9a" of theangular slot 9" is also horizontal but the draw straps are different,the straps 4 being eliminated and their function integrated into asingle pair of straps 6' which have an L-shaped configuration, the lowerparts 6a carry the magnet armature 3 directly thus eliminating the needfor guiding movement of the armature, which saves space and is moveeconomical, and the roll 5 being mounted for rotation about its axis atthe junction between the two parts 6a and 6b of the straps. As will beseen by comparison of FIG. 4 with FIG. 3, the upwardly extendingportions 6b of the draw straps in FIG. 4 likewise have a slightinclination relative to the vertical direction of movement of releaserod 7 and hence also only a small horizontal component of force isexerted on armature 3 in the break-a-way direction when the mechanism isin its hold position unstable equilibrium as depicted in the drawing.

We claim:

1. A device for initiating release of the contacts of an electricalswitch comprising an actuating rod tensioned in the upward releasedirection, and means retaining said actuating rod in a downward positionuntil released including a cylindric roll operable within a stationaryslate provided with an angular slot, said roll being coupled to saidactuating rod and being maintained in a state of unstable equilibrium bythe magnetic attractive .force of a hold-release magnet having anarmature to which said roll is also coupled, and said roll and angularslot being so designed that the upwardly directed tensional forceapplied to saidroll by said actuating rod exerts a relatively smallerhorizontal break-a-way component at the armature of said holdreleasemagnet.

2. A device as defined in claim 1 for initiating release of the contactsof an electrical switch wherein said angular slot includes an upper partextending upwardly and a lower part sloping slightly downward from thehorizontal, said roll being connected to said actuating rod by a firstpair of parallel spaced rigid straps pivotally connected at the oppositeends thereof to the opposite ends of said roll and to said actuatingrod, and said roll being pivotally connected to said magnet armature bya second pair of parallel spaced rigid straps connected at the oppositeends thereof to the opposite ends of said roll and magnet armature, andsaid roll being retained in the lower part of said slot in the holdposition of said magnet. 1

3. A device as defined in claim 1 for initiating release of the contactsof an electrical switch wherein said angular slot includes an upper partextending upwardly and a lower part extending horizontally, said rollbeing a connected to said actuating rod by a first pair of parallelspaced rigid straps pivotally connected at the opposite ends thereof tothe opposite ends of said roll and to actuating rod, and said roll beingpivotally connected to said magnet armature by a second pair of parallelspaced rigid straps connected at the opposite ends thereof to theopposite ends of said roll and armature, said roll being retained in thelower part of said slot in the hold position of said magnet, and saidfirst pair of straps being inclined at a slight angle to the verticaldirection of movement of said actuating rod in the hold position of saidmagnet. A

4. A device as defined in claim 1 for initiating release of the contactsof an electrical switch wherein said angular slot includes an upper partextending upwardly movement of said actuating rod in the hold positionof said magnet, and said roll being retained in the lower part of saidslot in the hold position of said magnet.

UNKTE STATES PATENT owict CEETEMCATJE CF CCECTWN v 7 Karl Buhler et a1.Inventor(s) It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Claim 1 line 6 "slate" should be plate Claim 4 (5th Column) line 3,"part should be said Signed and sealed. this 12th day of March 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM po'mso USCOMM-DC eoz-ne-pes i U.S. GOVERNMENT PRINTINGOFFICE: 1969 0-365-334,

lemme STATES PATENT oFF cE QERFEEFEQATE @F QGRRECTEQN Patnt N003,768,052 A Dated October 23, 1975 Karl Buhler et a1. Inventor(s) 1 Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Claim 1 line 6 slate should be plate Claim 4 -(5th Column) line 3,,"part" should be "said Signed and sealed. this 12th day of March 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 'fi' UvSA GOVERNMENTPRINTING OFFICE I969 0-366-334,

1. A device for initiating release of the contacts of an electricalswitch comprising an actuating rod tensioned in the upward releasedirection, and means retaining said actuating rod in a downward positionuntil released including a cylindric roll operable within a stationaryslate provided with an angular slot, said roll being coupled to saidactuating rod and being maintained in a state of unstable equilibrium bythe magnetic attractive force of a hold-release magnet having anarmature to which said roll is also coupled, and said roll and angularslot being so designed that the upwardly directed tensional forceapplied to said roll by said actuating rod exerts a relatively smallerhorizontal break-a-way component at the armature of said hold-releasemagnet.
 2. A device as defined in claim 1 for initiating release of thecontacts of an electrical switch wherein said angular slot includes anupper part extending upwardly and a lower part sloping slightly downwardfrom the horizontal, said roll being connected to said actuating rod bya first pair of parallel spaced rigid straps pivotally connected at theopposite ends thereof to the opposite ends of said roll and to saidactuating rod, and said roll being pivotally connected to said magnetarmature by a second pair of parallel spaced rigid straps connected atthe opposite ends thereof to the opposite ends of said roll and magnetarmature, and said roll being retained in the lower part of said slot inthe hold position of said magnet.
 3. A device as defined in claim 1 forinitiating release of the contacts of an electrical switch wherein saidangular slot includes an upper part extending upwardly and a lower partextending horizontally, said roll being connected to said actuating rodby a first pair of parallel spaced rigid straps pivotally connected atthe opposite ends thereof to the opposite ends of said roll and toactuating rod, and said roll being pivotally connected to said magnetarmature by a second pair of parallel spaced rigid straps connected atthe opposite ends thereof to the opposite ends of said roll andarmature, said roll being retained in the lower part of said slot in thehold position of said magnet, and said first pair of straps beinginclined at a slight angle to the vertical direction of movement of saidactuating rod in the hold position of said magnet.
 4. A device asdefined in claim 1 for initiating release of the contacts of anelectrical switch wherein said angular slot includes an upper partextending upwardly and a lower part extending horizontally, said rollhaving secured thereto at its opposite ends a pair of parallel spacedL-shaped rigid straps, the lower parts of said straps extendinghorizontally carrying the armature of said magnet, the upper parts ofsaid straps being pivotally secured to said actuating rod and disposedat a slight inclination relative to the vertical direction of movementof said actuating rod in the hold position of said magnet, and said rollbeing retained in the lower part of said slot in the hold position ofsaid magnet.